So is the old orc stable? And you can anchor his body? Can you get more Old Orc encounters than one? And also, will he increase in level later if you killed him at a low level? And does that guard set Mirmulnir drops count as an anchor?
I currently have the Old Orc anchored(treasure map from fort neugrad).
He must be at cap because he resisted Revenant.
In my experience , this type of NPC remained locked at the level they were when killed.
(at lvl 31) I have a number of such random lvl) thralls locked at low levels including Sild , Silus Vesuius , and The Caller.
Others like Arondil and Anska are capped like Old Orc.
Just a matter of chance but its does seem that the higher your own level , the more likely NPC will be high/capped.
I`ve read about Old Orc respawns but it`s never happened to me.
possible a patch changed things after those reports